The broad application of mobile devices has changed our life style gradually. For example, in the past, people used to write down notes of important events in calendars, while nowadays, people use electronic calendar function disposed in mobile devices (such as mobile phones and Personal Digital Assistances (PDAs)) to record those events. An electronic calendar provides a lot of convenience in event recording. By integrating the electronic calendar into a mobile device, a user can be reminded of his/her upcoming event. Thus, nowadays, many businessmen use the electronic calendar function provided by mobile devices to record various events, such as visiting customers, delivering goods, dating, and business trips, etc.
An important function of an electronic calendar is providing a reminding message to a user when the schedule of a stored event is due. The user may also set the reminding message to an earlier time (for example, 10 minutes earlier) so that the calendar can provide the reminding message at the set earlier time to remind the user in advance. However, even though the user can be reminded of an event through the method described above, the time it takes for the user to reach the event location is not considered. As a result, the user may be late for the event or even miss it. For example, if a user is visiting a customer at Taoyuan County and the calendar reminds the user that there will be a conference at Taipei 10 minutes later, the user will definitely be late for or even miss the event due to the long distance between the two places.